Hydraulic valves are connected to a pump and a tank and connected to movable members of construction and industrial equipment. Examples of these movable members are cylinders and hydraulic motors. The flow of fluid to and from each movable member is typically controlled by a control spool, which in turn is controlled manually or by hydraulic proportional pressure reducing valves, that themselves are controlled either manually or electro-hydraulically. The movement of the control spool, which resides in a bore inside the hydraulic valve assembly, opens and closes passages between the movable members and hoses or pipes that connect to a pump and a tank.
The valve assembly is a hydraulic devise that controls hydraulic fluid from a hydraulic pump to different movable members on construction and industrial equipment. Each movable member is controlled by a hydraulic section that consists of a body with a pair of work ports, and a pump inlet and tank outlet. A spool inside the body controls the flow of fluid to and from the different ports. An assembly can consist of a single section to operate a single movable member or a plurality of sections to operate a plurality of movable members. If multiple movable members are involved, one of the methods of controlling the fluid is an industry accepted hydraulic circuit identified as a series circuit. The series circuit allows the different movable member to be connected to each other by way of the valve assembly. This connection offers an advantage of recycling return flow from moving members that are activated to downstream moving members.